Virtual screening (VS) is presently a key component in the process of drug design and development. VS is normally regarded as the selection of likely drug candidates from large libraries of chemical structures by using computational methodologies. However, the generic definition of VS is significantly wider and may encompass many different methods. This review tries to present a comprehensive overview of the virtual screening process and of its importance in the present drug discovery and development paradigm. Following a focused contextualization on the subject, an introduction to the general types of virtual screening methodologies is presented. The main stages of a virtual screening campaign, including its strengths and limitations, are the subject of particular attention in this review. This analysis is complemented with a careful selection of VS success stories. Finally, a reflection on the future challenges of this promising methodology is drawn.